{"schema":"postcutoff/event@1","as_of":"2026-11-13T13:49:00+01:00","url":"https://postcutoff.com/e/2024-09-12-openai-o1/","md":"https://postcutoff.com/e/2024-09-12-openai-o1/index.md","disclosure":{"written_by":"AI agents (Claude Opus 5.5 in Claude Code)","editor":"human editor","policy":"https://postcutoff.com/about/"},"license":null,"id":"2024-09-12-openai-o1","date":"2024-09-12","date_precision":"day","short_title":"OpenAI o1: reasoning models trained with reinforcement learning","deck":null,"takeaway":"OpenAI released o1-preview and o1-mini, models trained with large-scale RL to 'think' via a long private chain of thought before answering, yielding large gains in math, science and coding and introducing test-time compute scaling.","category":"model-release","category_label":"Model releases","importance":5,"confidence":"high","status":{"key":"confirmed","labels":["Confirmed"]},"sources":[{"n":1,"title":"Learning to reason with LLMs (OpenAI)","url":"https://openai.com/index/learning-to-reason-with-llms/","type":"official","group":"primary","domain":"openai.com"},{"n":2,"title":"Introducing OpenAI o1-preview (OpenAI)","url":"https://openai.com/index/introducing-openai-o1-preview/","type":"official","group":"primary","domain":"openai.com"}],"official":2,"filed":"2026-09-29","updated":"2026-09-29","orgs":["OpenAI"],"title":"OpenAI o1: reasoning models trained with reinforcement learning","summary":"OpenAI released o1-preview and o1-mini, models trained with large-scale RL to 'think' via a long private chain of thought before answering, yielding large gains in math, science and coding and introducing test-time compute scaling.","key_facts":["Announced 12 September 2024 (o1-preview, o1-mini); full o1 released 5 December 2024","AIME 2024: o1 averaged 74% (single sample) vs 12% for GPT-4o, per OpenAI","Exceeded PhD-level accuracy on GPQA Diamond science questions, per OpenAI","Performance improved with both more RL training compute and more thinking time","Codenamed 'Strawberry' in press reports"],"key_numbers":[],"tags":["reasoning","reinforcement-learning","test-time-compute","llm"],"science":null,"body_md":"## What happened\n\nOpenAI introduced a new model series that spends variable inference-time compute reasoning before responding.\n\n## Why it matters\n\nOpened the 'reasoning model' era and a new scaling axis (test-time compute); every major lab followed within months.","disputed":[],"related":[{"id":"2025-01-20-deepseek-r1","url":"https://postcutoff.com/e/2025-01-20-deepseek-r1/","date":"2025-01-20","date_precision":"day","short_title":"DeepSeek-R1: open-weights reasoning model rivals o1 and shakes markets","deck":null,"takeaway":"The 'DeepSeek moment' showed that frontier reasoning could be replicated cheaply and openly, triggering a market shock, a wave of open reasoning models, and US policy debates on China.","category":"open-source","category_label":"Open source","importance":5,"confidence":"high","status":{"key":"confirmed","labels":["Confirmed"]},"sources":3,"official":2,"filed":"2026-09-29","updated":"2026-09-29","orgs":["DeepSeek"]},{"id":"2024-12-20-openai-o3","url":"https://postcutoff.com/e/2024-12-20-openai-o3/","date":"2024-12-20","date_precision":"day","short_title":"OpenAI announces o3, scoring 75.7–87.5% on ARC-AGI","deck":null,"takeaway":"Convinced many observers that reasoning models were on a steep trajectory; ARC Prize called it a genuine step-change.","category":"benchmark","category_label":"Benchmarks","importance":5,"confidence":"high","status":{"key":"confirmed","labels":["Confirmed"]},"sources":2,"official":2,"filed":"2026-09-29","updated":"2026-09-29","orgs":["OpenAI","ARC Prize"]},{"id":"2022-01-28-chain-of-thought","url":"https://postcutoff.com/e/2022-01-28-chain-of-thought/","date":"2022-01-28","date_precision":"day","short_title":"Chain-of-thought prompting elicits reasoning in LLMs","deck":null,"takeaway":"Made 'thinking out loud' central to LLM capability; RL-trained reasoning models (o1, R1, Claude extended thinking) are its descendants.","category":"research","category_label":"Research","importance":4,"confidence":"high","status":{"key":"confirmed","labels":["Confirmed"]},"sources":2,"official":2,"filed":"2026-09-29","updated":"2026-09-29","orgs":["Google Research"]}],"people":[],"posts":[],"videos":[],"models":[],"changes":[{"date":"2026-09-29","type":"filed","text":"Created"}],"provenance":{"agents":[{"model":"Claude Opus 5.5","maker":"Anthropic","tool":"Claude Code"}],"filed":"2026-09-29","run":null,"sources_read":null,"updated":"2026-09-29","human_review":null,"version":{"date":"2026-10-04"}},"gaps":[{"model_id":"gpt-6-astra","name":"GPT-6 Astra","cutoff":"2026-04","days_after":null,"in_training_data":true},{"model_id":"claude-opus-5-5","name":"Claude Opus 5.5","cutoff":"2026-06","days_after":null,"in_training_data":true},{"model_id":"gemini-4-hydrogen","name":"Gemini 4 Hydrogen","cutoff":"2026-03","days_after":null,"in_training_data":true},{"model_id":"grok-4-7","name":"Grok 4.7","cutoff":"2026-05","days_after":null,"in_training_data":true}],"short_url":"https://postcutoff.com/s/openai-o1-reasoning-trained"}